RICHARD AMBROSE (V/O): Now it's time to look at an everyday object using an infra red camera.

RICHARD AMBROSE (PTC): Hot things give off lots of infra red while cold things give off less.\u00a0 And this camera can actually do what our eyes can't.\u00a0 It can see the variations in temperature.

RICHARD AMBROSE (V/O): Today we're going to point it at our 850 watt microwave oven while we cook our dinner.

JONNY PHILLIPS (SYNC): Lovely.\u00a0 And on.

RICHARD (V/O): Microwaves cook by firing electro magnetic radiation at the molecules in food, causing them to vibrate and heat up. Opening up a microwave to look at its innards isn't recommended, but our camera reveals the location of the hot magnetron core that creates the microwaves. Microwave windows are lined with a mesh which ensures the radiation is contained. The whole oven is like a mini Faraday cage, built so no microwaves can escape. The red area isn't radiation leaking out, just some of the heat transferring to the outside panel.

JONNY (SYNC - TO RICHARD): See what happens if you touch the door?

RICHARD: I've got very cold hands.

JONNY: Take them away.

RICHARD (V/O): Most people think microwaves cook things from the inside out when they actually warm the surface of the food first.\u00a0 Although this never turns brown because the surrounding air is never warmed up.

RICHARD (V/O): My hands are at 13 degrees Celsius.\u00a0 The heat transfer from the Yorkshire pudding has made my fingertips rise to 25 degrees in just five seconds.\u00a0 And remember, unlike me always allow cooling time.